Power converter

The following description relates to a power converter.

Japanese Laid-Open Patent Publication No. 2010-259274 discloses a power converter that includes an inverter, an input capacitor, a relay, an inrush current limiter, and a charger. The inverter converts direct current (DC) power received from a battery into alternating current (AC) power and outputs the AC power. The input capacitor is located between the battery and the inverter. The relay is arranged in an interconnection connecting the battery and the inverter. The inrush current limiter includes a switch and a resistance element. The switch and the resistance element are connected in series to each other. The inrush current limiter is connected in parallel to the relay. When activating the inverter, the switch is turned on to pre-charge the input capacitor via the resistance element. This allows the inrush current limiter to limit inrush current. The charger converts AC power received from an external AC power supply into DC power and outputs the DC power. The battery is charged with the DC power output from the charger.

When charging the battery with the charger, current also flows through a capacitor of the charging device. To limit inrush current when charging the battery with the charger, the capacitor of the charger should also be provided with an inrush current limiter. In this case, separate inrush current limiters will have to be provided for the input capacitor and for the capacitor of the charger. This may enlarge the power conversion device.

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

In one general aspect, a power converter includes a charger, a battery, a first capacitor, an inverter, a second capacitor, a motor, a positive conductor, a negative conductor, a first switching unit, a connection line, a second switching unit, an interconnection, a third switching unit, an inrush current limiter, and processing circuitry. The charger is configured to convert input alternating current (AC) power into direct current (DC) power. The battery is configured to be supplied with DC power that is output from the charger. The first capacitor is arranged between the charger and the battery. The inverter is configured to be supplied with DC power that is output from the battery. The second capacitor is arranged between the battery and the inverter. The motor includes three star-connected coils and is configured to be supplied with AC power that is output from the inverter. The positive conductor is configured to connect the charger to a positive electrode of the battery. The negative conductor is configured to connect the charger to a negative electrode of the battery. The first switching unit is arranged in the positive conductor and configured to be turned on to connect the charger to the battery and turned off to disconnect the charger from the battery. The connection line is configured to connect a node between the charger and the first switching unit in the positive conductor to a neutral point of the motor. The second switching unit is arranged in the connection line and configured to be turned on to connect the positive conductor to the neutral point of the motor and turned off to disconnect the positive conductor from the neutral point of the motor. The interconnection is configured to connect the battery to the second capacitor. The third switching unit is arranged in the interconnection and configured to be turned on to connect the battery to the second capacitor and turned off to disconnect the battery from the second capacitor. The inrush current limiter is connected in parallel to the third switching unit and includes a resistance element and a fourth switching unit that is configured to be turned on to connect the battery via the resistance element to the second capacitor and turned off to disconnect the battery from the second capacitor. The processing circuitry is configured to pre-charge the second capacitor by turning off the third switching unit and turning on the fourth switching unit. Further, the processing circuitry is configured to pre-charge the first capacitor after pre-charging the second capacitor by performing a step-down operation with the inverter while turning on the second switching unit and the third switching unit and turning off the first switching unit and the fourth switching unit.

Other features and aspects will be apparent from the following detailed description, the drawings, and the claims.

Throughout the drawings and the detailed description, the same reference numerals refer to the same elements. The drawings may not be to scale, and the relative size, proportions, and depiction of elements in the drawings may be exaggerated for clarity, illustration, and convenience.

This description provides a comprehensive understanding of the methods, apparatuses, and/or systems described. Modifications and equivalents of the methods, apparatuses, and/or systems described are apparent to one of ordinary skill in the art. Sequences of operations are exemplary, and may be changed as apparent to one of ordinary skill in the art, with the exception of operations necessarily occurring in a certain order. Descriptions of functions and constructions that are well known to one of ordinary skill in the art may be omitted.

Exemplary embodiments may have different forms, and are not limited to the examples described. However, the examples described are thorough and complete, and convey the full scope of the disclosure to one of ordinary skill in the art.

One embodiment of a power converter will now be described. In this example, the power converter is installed in a vehicle.

Power Converter

As shown in, a power converterincludes a charger, an AC filter, a first capacitor C, a DC filter, a battery pack, an inverter circuit, and a motor. The inverter circuitincludes an inverterand a second capacitor C.

The chargerconverts input alternating current (AC) power into direct current (DC) power. The chargerof this embodiment includes an AC/DC converter, a capacitor C, and a DC/DC converter.

An external AC power supply AS, which is located outside a vehicle, supplies AC power that is input to the charger. The input AC power from the external AC power supply AS may be three-phase AC or single-phase AC.

The AC filterreduces noise emitted from the external AC power supply AS.

The AC/DC converterincludes two reactorsandand two series-connected bodiesand. A first end of the reactorand a first end of the reactorare connected to the AC filter. This connects the reactorsandvia the AC filterto the external AC power supply AS.

The two series-connected bodiesandare connected in parallel to each other. The series-connected bodyincludes two switching elements Qand Qthat are connected in series to each other. A second terminal of the reactoris connected to a node of the two switching elements Qand Q. The switching elements Qand Qare, for example, semiconductor switching elements. A semiconductor switching element is, for example, a metal-oxide semiconductor field-effect transistor MOSFET), an insulated-gate bipolar transistor (IGBT), a gallium nitride high electron mobility transistor (Gan HEMT), or the like.

The series-connected bodyincludes two switching elements Qand Qthat are connected in series to each other. A second terminal of the reactoris connected to a node of the two switching elements Qand Q. The switching elements Qand Qare, for example, semiconductor switching elements.

The AC/DC converterimproves the power factor, while converting the input AC power, which is received via the AC filter, into DC power.

The capacitor Cis arranged between the AC/DC converterand the DC/DC converter. The capacitor Cis a link capacitor or a smoothing capacitor.

One end of the capacitor Cis connected to a node of the switching elements Qand Q.

The other end of the capacitor Cis connected to a node of the two switching elements Qand Q.

The series-connected bodiesandare connected in parallel to the capacitor C.

The DC/DC converterincludes a first bridge circuit, a second bridge circuit, and a transformer. The first bridge circuitincludes two series-connected bodiesand. The two series-connected bodiesandare connected in parallel to each other. The series-connected bodyincludes two switching elements Qand Qthat are connected in series to each other. The switching elements Qand Qare, for example, semiconductor switching elements.

The series-connected bodyincludes two switching elements Qand Qthat are connected in series to each other. The switching elements Qand Qare, for example, semiconductor switching elements.

A node of the two switching elements Qand Qis connected to one end of the capacitor C.

A node of the two switching elements Qand Qis connected to the other end of the capacitor C.

The series-connected bodiesandare connected in parallel to the capacitor C.

The second bridge circuitincludes two series-connected bodiesand. The two series-connected bodiesandare connected in parallel to each other. The series-connected bodyincludes two switching elements Qand Qthat are connected in series to each other. The switching elements Qand Qare, for example, semiconductor switching elements.

The series-connected bodyincludes two switching elements Qand Q. The switching elements Qand Qare, for example, semiconductor switching elements.

The transformerincludes a first windingand a second winding. One end of the first windingis connected to a node of the two switching elements Qand Q. Another end of the first windingis connected to a node of the two switching elements Qand Q. One end of the second windingis connected to a node of the two switching elements Qand Q. The other end of the second windingis connected to a node of the two switching elements Qand Q.

The first capacitor Cis a link capacitor or a smoothing capacitor.

One end of the first capacitor Cis connected to a node of the two switching elements Qand Q, and the other end of the first capacitor Cis connected to a node of the two switching elements Qand Q.

The series-connected bodiesandare connected in parallel to the first capacitor C.

The DC filteris arranged between the series-connected bodyand the battery pack. The DC filterreduces noise included in the DC power output from the series-connected bodyand outputs the DC power to the battery pack.

The battery packincludes a battery, a first positive conductor L, a second positive conductor L, a first negative conductor L, a second negative conductor L, and first to fourth switchesto.

The batteryincludes rechargeable batteries that can be charged and discharged. The positive electrode of the batteryis connected to the first positive conductor L. The negative electrode of the batteryis connected to the first negative conductor L. The first capacitor Cis arranged between the chargerand the battery.

The first positive conductor Lserves as a positive conductor configured to connect the chargerto the positive electrode of the battery. The first negative conductor Lserves as a negative conductor configured to connect the chargerto the negative electrode of the battery. In this embodiment, the first positive conductor Land the first negative conductor Lconnect the DC filterand the battery. The batteryis supplied with the DC power output from the charger.

The first switchis arranged in the first positive conductor L. The first switchis, for example, a relay switch. The first switch, which is arranged in the first positive conductor L, acts as a first switching unit that is switchable to connect or disconnect the chargerand the battery. The first switchis turned on to connect the chargerto the batteryand turned off to disconnect the chargerfrom the battery.

The second switchis arranged in the first negative conductor L. The second switchis, for example, a relay switch. The second switchis switchable to connect or disconnect the chargerand the battery. The second switchis turned on to connect the chargerto the batteryand turned off to disconnect the chargerfrom the battery.

The second positive conductor Lconnects the positive electrode of the batteryand the inverter. The second negative conductor Lconnects the negative electrode of the batteryand the inverter.

The third switchis arranged in the second positive conductor L. The third switchis, for example, a relay switch. The third switchis switchable to connect or disconnect the batteryand the inverter. The third switchis turned on to connect the batteryto the inverterand turned off to disconnect the batteryfrom the inverter.

The fourth switchis arranged in the second negative conductor L. The fourth switchis, for example, a relay switch. The fourth switchis switchable to connect or disconnect the batteryand the inverter. The fourth switchis turned on to connect the batteryto the inverterand turned off to disconnect the batteryfrom the inverter.

The inverteris a three-phase inverter. The inverterincludes three series-connected bodies,, and. The series-connected bodies,, andare connected in parallel to one another. The series-connected bodyincludes a U-phase upper-arm switching element Qand a U-phase lower-arm switching element Q. The U-phase upper-arm switching element Qand the U-phase lower-arm switching element Qare connected in series between the second positive conductor Land the second negative conductor L. The series-connected bodyincludes a V-phase upper-arm switching element Qand a V-phase lower-arm switching element Q. The V-phase upper-arm switching element Qand the V-phase lower-arm switching element Qare connected in series between the second positive conductor Land the second negative conductor L. The series-connected bodyincludes a W-phase upper-arm switching element Qand a W-phase lower-arm switching element Q. The W-phase upper-arm switching element Qand the W-phase lower-arm switching element Qare connected in series between the second positive conductor Land the second negative conductor L. The U-phase upper-arm switching element Q, the U-phase lower-arm switching element Q, the V-phase upper-arm switching element Q, the V-phase lower-arm switching element Q, the W-phase upper-arm switching element Q, and the W-phase lower-arm switching element Qare, for example, semiconductor switching elements. The inverteris connected by the second positive conductor Land the second negative conductor Lto the battery.

The second capacitor Cis arranged between the batteryand the inverter. The second capacitor Chas one end connected to the second positive conductor Land another end connected to the second negative conductor L. The second capacitor Cis a smoothing capacitor or a link capacitor.

The motoris a three-phase motor. The motorincludes three coils,, and. The three coils,, andare star-connected. A first end of the coilis connected to a node of the U-phase upper-arm switching element Qand the U-phase lower-arm switching element Q. A first end of the coilis connected to a node of the V-phase upper-arm switching element Qand the V-phase lower-arm switching element Q. A first end of the coilis connected to a node of the W-phase upper-arm switching element Qand the W-phase lower-arm switching element Q. A second end of the coil, a second end of the coil, and a second end of the coilare connected to one another. A node of the second end of the coil, the second end of the coil, and the second end of the coilis a neutral point N of the motor.

The power converterincludes a connection line. The connection lineconnects a node between the chargerand the first switchin the first positive conductor Lto the neutral point N of the motor.

The power converterincludes a second switching unit. The second switching unitis arranged in the connection lineto connect or disconnect the first positive conductor Land the neutral point N of the motor. The second switching unitis, for example, a relay switch. The second switching unitis turned on to connect the first positive conductor Lto the neutral point N of the motorand turned off to disconnect the first positive conductor Lfrom the neutral point N of the motor.

The second positive conductor Land the second negative conductor Lconnect the batteryand the second capacitor C. The second negative conductor Lis an interconnection connecting the batteryand the second capacitor C. The fourth switchacts as a third switching unit that is switchable to connect or disconnect the batteryand the second capacitor C. The fourth switchis turned on to connect the batteryto the second capacitor Cand turned off to disconnect the batteryfrom the second capacitor C.

The battery packincludes an inrush current limiter. The inrush current limiteris connected in parallel to the fourth switch. The inrush current limiterincludes a resistance elementand a fourth switching unit. The fourth switching unitand the resistance elementare connected in series to each other. The fourth switching unitis switchable to connect or disconnect the batteryand the second capacitor Cvia the resistance element. The fourth switching unitis turned on to connect the batteryto the second capacitor Cvia the resistance elementand turned off to disconnect the batteryfrom the second capacitor C.